flowctrl2 subcommand fails with: `TypeError: only_relays_with_bandwidth() got multiple values for argument 'min_bw'`

This has been introduced by dc06bbdc. We changed a couple of the calls to stem_utils.only_relays_with_bandwidth but there are more.

I don't think we need to release another bugfix version because this doesn't affect the scanner nor the generator.

If needed, we could also just separate the script with little effort.